The present invention relates to an image recording apparatus, and more particularly, to an exposure unit of the image recording apparatus eliminating mechanical interference between a photosensitive pressure sensitive recording medium and an original or an original supporting member.
In the image recording apparatus, two types of image recording mediums are used, one is a self-contained type recording medium and the other is a transfer type recording medium. In the self-contained type recording medium, an encapsulated chromogenic material or dye precursor and a developer material are co-deposited on one surface of a single substrate as one layer or as two contiguous layers as disclosed in U.S. Pat. No. 4,440,846. In the transfer type recording medium, the developer material is coated on a separate substrate as a separate developer or copy sheet as described in U.S. Pat. No. 4,399,209.
Generally, the recording medium is subjected to light exposure for forming a latent image thereon corresponding to an original at an exposure unit, so that the light-exposed microcapsules are photo-cured, and in the subsequent pressure application at a pressure developing unit, non-photocured microcapsules are ruptured to react with the developer material to provide a visible image on the recording medium (self-contained type) or on the separate developer sheet (in the transfer-type).
In the light exposure unit, the original is brought into close contact with the photosensitive recording meidum. In this case, if the recording medium has sufficient hardness such as diazo photosensitive medium, the latter would not be easily injured, and therefore, it is unnecessary to protect the photosensitive surface of the recording medium. On the other hand, if a photosensitive recording medium having low hardness is applied, the recording medium may be disadvantageously formed with a scar due to frictional contact with the original. In this connection, conventional rollers for providing a superposition between the original and the recording medium may not be available for such low hardness recording medium.
In several cases, the original is protected by being sandwiched by an original supporting sheet member, and the original supporting member mounting the original is inserted into the image recording apparatus and is positioned onto an exposure table at which the recording meidum is brought into intimate contact with the original supporting member for light exposure. In this respect, according to a conventional image recording apparatus, the exposure table is positioned lower than that of the ambient mechanical components. However, such low positional setting of the exposure table may provide a stepped portion, so that it would be rather difficult to automatically install a new rolled image recording medium onto the recording apparatus, and particularly, it would be difficult to permit the reading end of the medium to pass through the exposure unit and to direct the same toward the pressure developing unit due to undesirable guiding by the stepped portion.